The CELP type voice encoding device divides a voice into certain frame lengths, linearly predicts the voice in each frame and encodes a prediction residue (activating signal) resulting from the linear prediction for each frame by using an adaptive code vector and a noise code vector constituted of known waveforms. For the adaptive code vector and the noise code vector, as shown in FIG. 34, the adaptive code vector and the noise code vector which are stored in an adaptive code book 1 and a noise code book 2, respectively, are used as they are in some case. As shown in FIG. 35, in another case used are the adaptive code vector from the adaptive code book 1 and the noise code vector from the noise code book 2 which is synchronized with a pitch cycle L of the adaptive code book 1. FIG. 35 shows a constitution of a noise sound source vector generating portion in the CELP type voice encoding device which is disclosed in publications of Patent Application Laid-open No. Hei 5-19795 and Hei 5-19796. In FIG. 35, the adaptive code vector is selected from the adaptive code book 1, while the pitch cycle L is emitted. The noise code vector selected from the noise code book 2 is made periodic by a periodic unit 3 using the pitch cycle L. To make periodic the noise code vector, the vector is cut by the pitch cycle from its top and repeatedly connected plural times until a sub-frame length is reached.
However, in the aforementioned conventional CELP type voice encoding device in which the noise code vector is pitch-cycled, after an adaptive code vector component is removed, a residual pitch cycle component is removed by making periodic the noise code vector in the pitch cycle. Therefore, phase information which exists in one pitch waveform, that is, the information representing where a pitch pulse peak exists is not positively used. Therefore, enhancement of voice quality has been restricted.
The present invention has been developed to solve the conventional problem, and an object thereof is to provide a voice encoding device which can further enhance a voice quality.